When I brew 5-5.5 gallons, I actually mean 5 U.S. gallons anyway, since I use Better Bottles to ferment (6 U.S. gallons), and could never fit 23 L in there with enough headspace, anyway.
I, too, end up giving a lot of homebrew away, even though I sometimes find when a batch is running out, I almost start thinking of the rest of the bottles as little children... just can't stand seeing them go off from home <sniff>.
4-hour bottling session? Ouch! I can see why you keg! For me, it's always been at the end of my "want-list" since I started brewing a little over a year ago, mainly due to that I wouldn't trust myself with kegs in the house. When I bottle, it takes about 30 minutes to sanitize everything, and 1 hour tops for racking, bottling, and clean-up (thanks to help from my wife), so I don't mind it that much at all.